580 lines
14 KiB
Java
580 lines
14 KiB
Java
package redis.clients.util;
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import java.util.HashMap;
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import java.util.Timer;
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import java.util.TimerTask;
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import java.util.concurrent.LinkedBlockingQueue;
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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.TimeoutException;
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/**
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* Abstract resource pool of type T.
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*
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* Needs implementation for creation, validation and destruction of the
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* resources.
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*
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* Keeps a fixed amount of resources
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*
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* @author Luis Dario Simonassi
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*
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* @param <T>
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* The type of the resource to be managed.
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*/
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public abstract class FixedResourcePool<T> {
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/*
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* Generic Inner Control Classes ------- ----- ------- ------- * Wrapper *
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* RepairThread
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*/
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/**
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* Generic Resource Wrapper
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*/
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private static class Wrapper<T> {
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long timestamp;
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T wrapped;
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public Wrapper(T wrapped) {
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this.wrapped = wrapped;
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mark();
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}
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public void mark() {
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timestamp = System.currentTimeMillis();
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}
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public long getLastMark() {
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return timestamp;
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}
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}
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/**
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* Generic Repair Thread
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*/
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protected class RepairThread extends Thread {
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public void run() {
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// Contribute to the repairing and validation effort until the pool
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// is destroyed (finishig=true)
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while (!finishing) {
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Wrapper<T> wrapper;
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try {
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// Remove the oldest element from the repair queue.
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wrapper = repairQueue.poll(timeBetweenValidation,
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TimeUnit.MILLISECONDS);
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if (wrapper == null) {
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// If I've been waiting too much, i'll check the idle
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// pool if connections need
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// validation and move them to the repair queue
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checkIdles();
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continue;
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}
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} catch (InterruptedException e) {
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continue;
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}
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// Now, I have something to repair!
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T resource = wrapper.wrapped;
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boolean valid = false;
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// Resources are null right after initialization, it means the
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// same as being an invalid resource
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if (resource != null) {
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valid = isResourceValid(resource); // Validate the resource.
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if (!valid)
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fails++;
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}
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// If resource is invalid or null, create a new resource and
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// destroy the invalid one.
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if (!valid) {
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T replace = createResource();
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resourcesCreated++;
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wrapper.wrapped = replace;
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if (resource != null)
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destroyResource(resource);
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}
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// Mark the resource as fresh!
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wrapper.mark();
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// Offer the resource to the available resources pool.
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if (!availableQueue.offer(wrapper)) {
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System.err
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.println("This shouldn't happen, offering to available was rejected.");
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}
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}
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System.out.println("Ending thread ["
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+ Thread.currentThread().getName() + "]");
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}
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/**
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* Check if resources in the idle queue needs to be repaired
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*/
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private void checkIdles() {
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// Get a sample without removing it
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Wrapper<T> wrapper = availableQueue.peek();
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// If no available items, nothing to repair.
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if (wrapper == null)
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return;
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// Check if the sampled resource needs to be repaired
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boolean repairNeeded = isValidationNeeded(wrapper);
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if (!repairNeeded)
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return;
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// Move available resources from the available queue to the repair
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// queue until no repair is needed.
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while (repairNeeded) {
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// Get the connection from the available queue and check again.
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wrapper = availableQueue.poll();
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// No resources in the available queue, nothing to do
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if (wrapper == null) {
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repairNeeded = false;
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return;
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}
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// Add the resource to the corresponding queue, depending on
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// weather the resource needs to be repaired or not.
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repairNeeded = isValidationNeeded(wrapper);
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if (repairNeeded) {
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if (!repairQueue.offer(wrapper)) {
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System.err
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.print("FATAL: This shouldn't happen, offering to repairing was rejected.");
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}
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} else {
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if (!availableQueue.offer(wrapper)) {
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System.err
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.print("FATAL: This shouldn't happen, offering to available was rejected.");
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}
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}
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}
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}
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}
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/*
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* Pool metrics
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*/
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private volatile long failsReported = 0;
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private volatile long fails = 0;
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private volatile long resourcesCreated = 0;
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private volatile long resourcesProvided = 0;
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private volatile long resourcesReturned = 0;
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/*
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* Pool metrics accessing methods.
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*/
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public long getFailsReported() {
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return failsReported;
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}
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public long getFails() {
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return fails;
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}
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public long getResourcesCreated() {
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return resourcesCreated;
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}
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public long getResourcesProvided() {
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return resourcesProvided;
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}
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public long getResourcesReturned() {
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return resourcesReturned;
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}
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/*
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* Pool status structures
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*/
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private LinkedBlockingQueue<Wrapper<T>> availableQueue;
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private LinkedBlockingQueue<Wrapper<T>> repairQueue;
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private final HashMap<T, Wrapper<T>> inUse = new HashMap<T, Wrapper<T>>();
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private RepairThread[] repairThreads;
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private Timer t;
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private boolean initializated = false;
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private boolean finishing = false;
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/*
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* Pool configuration parameters
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*/
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private String name;
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private long defaultPoolWait = 50;
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private int resourcesNumber = 10;
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private int repairThreadsNumber = 3;
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private long timeBetweenValidation = 150000;
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/*
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* Bean pool configuration
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*/
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public int getResourcesNumber() {
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return resourcesNumber;
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}
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public void setResourcesNumber(int resourcesNumber) {
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this.resourcesNumber = resourcesNumber;
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}
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public int getRepairThreadsNumber() {
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return repairThreadsNumber;
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}
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public void setRepairThreadsNumber(int repairThreadsNumber) {
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if (initializated)
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throw new IllegalStateException(
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"Repair threads should be setted up before init()");
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this.repairThreadsNumber = repairThreadsNumber;
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}
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public long getTimeBetweenValidation() {
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return timeBetweenValidation;
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}
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public void setTimeBetweenValidation(long timeBetweenValidation) {
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this.timeBetweenValidation = timeBetweenValidation;
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}
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public void setName(String name) {
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if (initializated)
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throw new IllegalStateException(
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"Name should be setted up before init()");
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this.name = name;
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}
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public String getName() {
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if (name == null || name.isEmpty()) {
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name = this.getClass().getName();
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}
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return name;
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}
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public void setDefaultPoolWait(long defaultPoolWait) {
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this.defaultPoolWait = defaultPoolWait;
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}
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public long getDefaultPoolWait() {
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return defaultPoolWait;
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}
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/**
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* Pool initialization & destruction
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*/
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public void destroy() {
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checkInit();
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System.out.println("Destroying [" + getName() + "]...");
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// Signal al threads to end
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finishing = true;
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System.out.println("Destroying [" + getName() + "] threads");
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// Wait for the Repair Threas
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for (int i = 0; i < repairThreads.length; i++) {
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boolean joined = false;
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do {
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try {
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repairThreads[i].interrupt();
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repairThreads[i].join();
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joined = true;
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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} while (!joined);
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}
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System.out.println("Waiting for [" + getName()
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+ "] resources to be returned.");
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// Wait for all resources to be returned to the pool
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synchronized (this) {
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while (!inUse.isEmpty()) {
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try {
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this.wait();
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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}
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}
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System.out.println("Destroying [" + getName() + "] resources.");
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// Destroy resources
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for (Wrapper<T> resource : availableQueue) {
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destroyResource(resource.wrapped);
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}
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availableQueue.clear();
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availableQueue = null;
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for (Wrapper<T> resource : repairQueue) {
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destroyResource(resource.wrapped);
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}
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repairQueue.clear();
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repairQueue = null;
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// Destroy metrics timer
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System.out.println("Shuting metrics timer for [" + getName()
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+ "] down.");
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t.cancel();
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t = null;
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// Reset metrics
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failsReported = 0;
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fails = 0;
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resourcesCreated = 0;
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resourcesProvided = 0;
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resourcesReturned = 0;
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// Set states to initial values
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initializated = false;
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finishing = false;
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System.out.println("Pool [" + getName() + "] successfully destroyed.");
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}
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/**
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* Initialize the pool
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*/
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@SuppressWarnings("unchecked")
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public void init() {
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if (initializated == true) {
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System.err.println("Warning, double initialization of [" + this
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+ "]");
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return;
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}
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initializated = true;
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// Create queues with maximum possible capacity
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availableQueue = new LinkedBlockingQueue<Wrapper<T>>(resourcesNumber);
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repairQueue = new LinkedBlockingQueue<Wrapper<T>>(resourcesNumber);
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// Create and start the repair threads.
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repairThreads = new FixedResourcePool.RepairThread[repairThreadsNumber];
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for (int i = 0; i < repairThreads.length; i++) {
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repairThreads[i] = new RepairThread();
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repairThreads[i].setName("REPAIR[" + i + "]:" + getName());
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repairThreads[i].start();
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}
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// Create resource wrappers with null content.
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for (int i = 0; i < resourcesNumber; i++) {
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if (!repairQueue.offer(new Wrapper<T>(null)))
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throw new IllegalStateException(
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"What!? not enough space in the repairQueue to offer the element. This shouldn't happen!");
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}
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// Schedule a status report every 10 seconds.
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t = new Timer();
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t.schedule(new TimerTask() {
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@Override
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public void run() {
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System.out.println("**********************************");
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System.out.println("* Pool name:[" + name + "]");
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System.out.println("* resourcesCreated....:"
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+ getResourcesCreated());
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System.out.println("* failsReported.......:"
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+ getFailsReported());
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System.out.println("* fails...............:" + getFails());
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System.out.println("* resourcesCreated....:"
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+ getResourcesCreated());
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System.out.println("* resourcesProvided...:"
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+ getResourcesProvided());
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System.out.println("* resourcesReturned...:"
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+ getResourcesReturned());
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System.out.println("* available size......:"
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+ availableQueue.size());
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System.out.println("* repair size.........:"
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+ repairQueue.size());
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System.out.println("**********************************");
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}
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}, 10000, 10000);
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System.out.println("Initialized [" + name + "]");
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}
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protected void checkInit() {
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if (!initializated)
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throw new IllegalStateException("Call the init() method first!");
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}
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/**
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* Returns true if wrapped resource needs validation
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*
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* @param wrapper
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* @return
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*/
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private boolean isValidationNeeded(Wrapper<T> wrapper) {
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// Add noise to the check times to avoid simultaneous resource checking.
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long noisyTimeBetweenCheck = (timeBetweenValidation - (long) ((Math
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.random() - 0.5) * (timeBetweenValidation / 10)));
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// Check if the resource need to be checked.
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return wrapper.getLastMark() + noisyTimeBetweenCheck < System
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.currentTimeMillis();
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}
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/**
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* Return a resource to the pool. When no longer needed.
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*
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* @param resource
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*/
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public void returnResource(T resource) {
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checkInit();
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Wrapper<T> wrapper;
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if (resource == null)
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throw new IllegalArgumentException(
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"The resource shouldn't be null.");
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// Delete the resource from the inUse list.
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synchronized (inUse) {
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wrapper = inUse.remove(resource);
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}
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if (wrapper == null)
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throw new IllegalArgumentException("The resource [" + resource
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+ "] isn't in the busy resources list.");
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if (isValidationNeeded(wrapper)) {
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if (!repairQueue.offer(wrapper))
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throw new IllegalStateException(
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"This shouldn't happen. Offering to repair queue rejected.");
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} else {
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if (!availableQueue.offer(wrapper))
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throw new IllegalStateException(
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"This shouldn't happen. Offering to available queue rejected.");
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}
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resourcesReturned++;
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if (finishing) {
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synchronized (this) {
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this.notify();
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}
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}
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}
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/**
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* Return a broken resource to the pool. If the application detects a
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* malfunction of the resource. This resources will go directly to the
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* repair queue.
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*
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* @param resource
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*/
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public void returnBrokenResource(T resource) {
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checkInit();
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Wrapper<T> wrapper;
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// Delete the resource from the inUse list.
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synchronized (inUse) {
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wrapper = inUse.remove(resource);
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}
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if (wrapper == null)
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throw new IllegalArgumentException("The resource [" + resource
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+ "] isn't in the busy resources list.");
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if (!repairQueue.offer(wrapper))
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throw new IllegalStateException(
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"This shouldn't happen. Offering to repair queue rejected.");
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resourcesReturned++;
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if (finishing) {
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synchronized (this) {
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this.notify();
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}
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}
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}
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/**
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* Get a resource from the pool waiting the default time.
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* {@link #setDefaultPoolWait(long)}
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*
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* @return the resource of type T
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* @throws TimeoutException
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*/
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public T getResource() throws TimeoutException {
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return getResource(defaultPoolWait);
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}
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/**
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* Get a resource from the pool.
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*
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* @param maxTime
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* Max time you would like to wait for the resource
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* @return
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* @throws TimeoutException
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*/
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public T getResource(long maxTime) throws TimeoutException {
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if (finishing)
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throw new IllegalStateException("Pool [" + getName()
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+ "] is currently being destroyed.");
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checkInit();
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final long tInit = System.currentTimeMillis();
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do {
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try {
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long timeSpent = System.currentTimeMillis() - tInit;
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long timeToSleep = maxTime - timeSpent;
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timeToSleep = timeToSleep > 0 ? timeToSleep : 0;
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if (timeToSleep == 0)
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throw new TimeoutException("" + timeSpent + ">" + maxTime);
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Wrapper<T> ret = availableQueue.poll(timeToSleep,
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TimeUnit.MILLISECONDS);
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if (ret != null) {
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synchronized (inUse) {
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inUse.put(ret.wrapped, ret);
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}
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resourcesProvided++;
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return ret.wrapped;
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}
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} catch (InterruptedException e1) {
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e1.printStackTrace();
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} // If the wait gets interrupted, doesn't matter but print it (just
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// in case).
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} while (true);
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}
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/*
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* Implementation dependent methods. To be implemented.
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*/
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/**
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* Create a resource for the pool
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*/
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protected abstract T createResource();
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/**
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* Check if the resource is still valid.
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*
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* @param resource
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* @return
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*/
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protected abstract boolean isResourceValid(T resource);
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/**
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* Destroy a resource.
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*
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* @param resource
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*/
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protected abstract void destroyResource(T resource);
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@Override
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public String toString() {
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return getName() + "[" + super.toString() + "]";
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}
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/**
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* Coming features: TODO Busy time check. Cron to check when a resource is
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* being taken for a long time.
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*/
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}
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